The present invention concerns a method of constructing electric storage batteries. The cells of such batteries contain at least one positive electrode and at least one negative electrode and a separator to separate the electrodes. Each cell, however, commonly contains three to seven electrodes of each type. In lead storage batteries there is in each cell one negative electrode more than the number of positive electrodes. Each positive electrode is thus covered on each side by a separator which divides the positive electrode from the negative electrode. The area of the separators is somewhat larger than the area of the electrodes and it is important that the separators in the finished cell extend out beyond the electrodes by approximately an equal amount around the entire periphery of the electrodes. It is also important that all the electrodes in a cell be placed opposite one another. The invention concerns a method of constructing electric storage batteries by means of which electrode sets can be arranged and/or secured with electrodes and separators in the proper positions.
As mentioned above, it is important that electrodes and separators be placed in the proper position in relationship to one another in the battery cell. By means of the presence of the separator between the different electrodes, the electrolyte's electrical resistance to current between the electrodes is increased. In order to avoid high current densities and short circuits between the outer edges of the electrodes, the separators are made somewhat larger than the electrodes. These should therefore be placed so that they extend approximately an equal distance beyond the edge of the electrode around the entire periphery.
The connection of electrodes of the same type via a pole bridge in the cell is accomplished with various methods of construction just as the means of mounting the electrode set in the cell vessel varies. No matter what the method chosen, however, the electrode set must at some stage of construction be arranged so that the electrodes and the separators come into the proper position with respect to one another. One method of achieving this is to use holders for the electrode sets which are provided with combs, that is to say, strips which are provided with grooves for receiving the separators. The preparation of electrodes and separators involves, however, certain unavoidable variations, which lead to small variations in the thickness of the finished product. This in turn leads to problems with the use of combs for arranging the electrode sets.
One has, therefore, tried to find a construction method where one can avoid the use of combs as described above. One such method and apparatus therefor is described in Swedish patent No. 363,705. According to the method therein described, the positioning of the electrodes takes place with the help of so-called feet, that is, extensions of the lower surface of the electrodes. The separators are arranged with the help of guide strips.
It is, therefore, an object of the present invention to provide novel methods and apparatus for positioning electrodes relative to separators.
It is another object of the invention to provide such methods and apparatus which can eliminate the need for feet on the electrodes.